Flight Soekarno–Hatta International Airport departs from Jakarta Soekarno–Hatta International Airport at 18:00 and arrives at Medan Kualanamu International Airport at 20:20.
The flighttime is about 2h 20m. The distance travelled ("as the bird flies"): 895 Km. So the average speed is roughly 384 Km.
The best day to arrive at Jakarta is Saturday and it would be best to avoid Wednesday, as prices are on average 54.06% higher than on Saturday. (Average prices, based on 750456558 datapoints.)
We have a lot more statistics for flights JT 3308 and between Jakarta and Medan.